Columbia, MD and Puerto Rico—April 19, 2017. The Arecibo Observatory in Puerto Rico this week observed potentially hazardous near-Earth asteroid 2014 JO25 as part of its planetary radar program sponsored by NASA’s Near-Earth Object Observations (NEOO) program. Arecibo radar observations revealed the asteroid to have a lumpy, two-lobed shape very reminiscent of Comet 67P/Churyumov–Gerasimenko recently visited by the European Space Agency's Rosetta mission.

2014 JO25 was discovered in May 2014 by the Catalina Sky Survey and designated a potentially hazardous asteroid based on its size and relative proximity to Earth. Prior to radar measurements, its diameter was estimated using data from the NEOWISE spacecraft to be 650 meters (2130 feet), more than twice the size of the Arecibo dish. The Arecibo Observatory Planetary Radar system, which is the most sensitive and the most active in the world, has now provided direct measurements of the asteroid’s size, shape, rotation, and near-surface geology.

“Using radar, we can illuminate a near-Earth asteroid and directly measure its features. In this case, we found 2014 JO25 to be a contact-binary asteroid,” noted Dr. Edgard Rivera-Valentín, Planetary Scientist with the Universities Space Research Association (USRA) at Arecibo Observatory. “The asteroid is at least 650 m (2130 ft) long," continued Rivera-Valentín. Additionally, Arecibo data suggests 2014 JO25 rotates approximately once every 4.5 hours.

Delay-Doppler images of 2014 JO25 captured with the Arecibo Observatory Planetary Radar System on April 17 and 20 UT. In these animations, the two-lobed shape of this asteroid is readily visible and reminiscent of Comet 67P/Churyamov-Gerasimenko. Each animation spans ~2 hours of observations and have vertical resolution of 7.5 m/pixel.

Not all asteroids are spherical. In fact, Dr. Patrick Taylor, Group Lead for Planetary Radar at Arecibo notes, “About 1 in 6 near-Earth asteroids are contact binaries, which could have formed as two asteroids failed at orbiting each other and fell back together. There are as many of these contact binaries as there are true binaries, asteroids with their own moons.”

“Because radar can very precisely measure an asteroid’s distance from Earth and how fast it is moving, we can better predict where this object will be in the future,” said Luisa Fernanda Zambrano-Marin, graduate student and researcher with USRA at Arecibo. “The data we provide to NASA’s NEOO program helps us evaluate an asteroid’s impact hazard to Earth and helps NASA evaluate appropriate deflection strategies if needed,” continued Zambrano-Marin.

Though designated as potentially hazardous, asteroid 2014 JO25 is not a threat to Earth at this time and safely passed by Earth on April 19 at 4.6 times the distance between the Earth and Moon.

Current models predict it will not make a similar close approach to Earth for several hundred years. According to NASA, the next known close approach by an object of similar size is in August 2027 by asteroid 1999 AN10, which is estimated to be more than 700 m (2300 ft) in diameter.

Complementary radar observations of 2014 JO25 are underway at NASA’s Goldstone Solar System Radar Complex located in the Mojave Desert of California.

Mosiac of delay-Doppler images taken using the Arecibo Planetary Radar system on April 17, 2017

About Arecibo

The Arecibo Observatory is a facility of the National Science Foundation (NSF) operated under cooperative agreement by SRI International in alliance with Universities Space Research Association (USRA) and Universidad Metropolitana. The Arecibo Observatory Planetary Radar Program is fully supported by the National Aeronautics and Space Administration (NASA) by grants from the Near-Earth Object Observations program to USRA.

About USRA

Universities Space Research Association is an independent, nonprofit research corporation where the combined efforts of in-house talent and university-based expertise merge to advance space science and technology. USRA works across disciplines including biomedicine, planetary science, astrophysics, and engineering and integrates those competencies into applications ranging from fundamental research to facility management and operations. USRA engages the creativity and authoritative expertise of the research community to develop and deliver sophisticated, forward-looking solutions to Federal agencies and other government sponsors.